KR100668321B1 - Fuel cell electrode containing metal phosphate and fuel cell using the same - Google Patents

Abstract

The present invention relates to an electrode of a fuel cell, and more particularly, to a fuel cell electrode including a proton conductor of a fuel cell that maintains excellent electrical conductivity even at high temperatures, and a fuel cell employing such an electrode.

In the present invention, since the metal phosphate is used as the proton conductor, it is possible to obtain an electrode having excellent ion conductivity under low temperature and high humidity conditions, low electrical resistance, and high potential under the same conditions. A fuel cell electrode can be obtained.

Proton Conductors, Metal Phosphates, Electrodes, Fuel Cells, Phosphoric Acid

Description

Fuel cell electrode using metal phosphate and fuel cell employing the same {Fuel cell electrode containing metal phosphate and fuel cell using the same}

1 is an XRD graph of a supported catalyst-metal phosphate complex prepared according to Example 1 of the present invention.

2 is a graph showing the performance of a fuel cell manufactured according to Example 7 of the present invention.

The present invention relates to an electrode of a fuel cell, and more particularly, to a fuel cell electrode including a proton conductor of a fuel cell that maintains excellent electrical conductivity even at high temperatures, and a fuel cell employing such an electrode.

A fuel cell is a device that produces electrical energy by electrochemically reacting fuel and oxygen. Unlike thermal power generation, a fuel cell does not undergo a carnocycle, and thus its theoretical power generation efficiency is very high. Fuel cells can be applied not only as a source of power for industrial, domestic and vehicle driving, but also as a power source for small electrical / electronic products, especially portable devices.

Fuel cells can be classified into PEM (polymer electrolyte membrane), phosphoric acid, molten carbonate, solid oxide, etc., depending on the type of electrolyte used. In addition, the operating temperature of the fuel cell and the material of the component are changed depending on the electrolyte used.

In PEMFC, as a material of the polymer electrolyte membrane, generally a polymer such as a sulfonate high fluorinated polymer having a main chain composed of fluorinated alkylene and a side chain composed of fluorinated vinyl ether having a sulfonic acid group at its terminal (e.g., Nafion: trademark of Dupont) Electrolytes have been used. It is to be noted that such a polymer electrolyte membrane exhibits excellent ion conductivity by impregnating an appropriate amount of water.

In the PEMFC employing such a polymer electrolyte membrane, when the proton generated at the anode moves to the cathode, water is accompanied by osmotic drag, so that the anode side of the polymer electrolyte membrane is dried. The conductivity drops sharply and, in severe cases, the PEMFC becomes inoperable. In addition, when the operating temperature of the PEMFC is a high temperature of about 80 to 100 ° C. or more, due to the evaporation of water from the polymer electrolyte membrane, the drying of the polymer electrolyte membrane is intensified, whereby the proton conductivity of the polymer electrolyte membrane is further drastically lowered.

Conventional PEMFCs have been operated mainly at temperatures below 100 ° C., for example at about 80 ° C., due to such drying problems of polymer electrolyte membranes. However, due to the low operating temperature of about 100 ℃ or less, the following problems are known to occur. That is, hydrogen-rich gas, which is a representative fuel of PEMFC, is obtained by reforming an organic fuel such as natural gas or methanol. The hydrogen-enriched gas contains carbon monoxide as well as carbon dioxide as a by-product. Carbon monoxide tends to poison the catalyst contained in the cathode and anode. The electrochemical activity of catalysts poisoned with carbon monoxide is greatly degraded, thereby significantly reducing the operational efficiency and lifetime of the PEMFC. Note that the tendency of carbon monoxide to poison the catalyst is aggravated at lower operating temperatures of the PEMFC.

The catalyst poisoning phenomenon by carbon monoxide occurs similarly when methanol, which is another representative fuel of PEMFC, is used as a fuel. Methanol is fed to the anode of PEMFC in the form of an aqueous methanol solution (or a mixed vapor of water and methanol). Methanol and water react at the anode to produce hydrogen ions and electrons, which produce carbon monoxide as well as carbon dioxide.

When the operating temperature of the PEMFC is raised to about 150 ° C. or more, catalyst poisoning by carbon monoxide can be avoided, and the temperature control of the PEMFC is also very easy, thereby miniaturizing the fuel reformer and simplifying the cooling device. The entire PEMFC power generation system can be miniaturized. However, in the case of a polymer electrolyte such as a conventional general electrolyte membrane, that is, a sulfonate high fluorinated polymer having a main chain composed of fluorinated alkylene and a side chain composed of fluorinated vinyl ether having a sulfonic acid group at its end (e.g., Nafion: trademark of Dupont) As described above, the operation at a high temperature was almost impossible because the performance deterioration due to the evaporation of moisture at a high temperature was severe. For this reason, there is a growing interest in PEMFCs capable of operating at high temperatures.

Proton conductive inorganic compounds as well as various polymer electrolytes have been proposed as materials for a non-humidified electrolyte membrane. Thus, the concept of PEMFC has been extended to proton exchange membrane fuel cells, including polymer electrolyte membrane fuel cells.

As the non-humidifying polymer electrolytes, polybenzimidazole / strong acid complexes, polysyramine / strong acid complexes, basic polymers / acid polymer complexes, polytetrafluoroethylene porous electrolyte membranes processed from these, and electrolyte membranes reinforced with apatite have been studied. [USP 5,525,436, USP 6,187,231, USP 6,194,474, USP 6,242,135, USP 6,300,381, USP 6,365,294].

Although it is noted that such a non-humidified polymer electrolyte or a proton conductive inorganic compound plays a key role in implementing a PEMFC capable of operating at a high temperature, there is still room for improvement in terms of electrical conductivity.

The first technical problem to be achieved by the present invention is to provide an electrode for a fuel cell that can operate at high temperatures.

The second technical problem to be achieved by the present invention is to provide a method for manufacturing the electrode for a fuel cell.

The third technical problem to be achieved by the present invention is to provide a fuel cell having improved performance at high temperatures by employing the fuel cell electrode.

The present invention to achieve the first technical problem, the metal catalyst; A carrier for supporting the metal catalyst; A proton conductor made of metal phosphate; Provided is a fuel cell electrode comprising a catalyst layer containing a binder and a gas diffusion layer made of a conductive substrate.

According to the above structure, it is possible to obtain a fuel cell electrode that maintains high ion conductivity even at high temperatures.

The present invention to achieve the second technical problem,

(a-1) preparing a supported catalyst-metal oxide complex in which a supported catalyst consisting of a metal catalyst and a carrier supporting the same and a metal solution are mixed, and adjusting a pH to precipitate a metal oxide of the metal solution on the supported catalyst;

(b-1) separating the supported catalyst-metal oxide complex produced in (a-1);

(c-1) preparing a metal catalyst precursor by mixing the supported catalyst-metal oxide complex separated in (b-1) with phosphoric acid and a dispersant;

(d-1) heat treating the metal catalyst precursor prepared in (c-1) to obtain a supported catalyst-metal phosphate complex;

(e-1) mixing the supported catalyst-metal phosphate complex, the binder and the solvent produced by the heat treatment in (d-1):

(f-1) providing a fuel cell electrode manufacturing method comprising the step of manufacturing the electrode by coating the resultant prepared in the above (e-1) on the gas diffusion layer.

According to the above configuration, it is possible to manufacture a fuel cell electrode exhibiting high ion conductivity even at high temperatures.

The present invention also to achieve the second technical problem,

(a-2) mixing the supported catalyst and the metal solution on which the metal catalyst is supported, and adjusting the pH to prepare a supported catalyst-metal oxide complex in which the metal oxide of the metal solution is precipitated on the supported catalyst;

(b-2) separating the supported catalyst-metal oxide complex produced in (a-2);

(c-2) heat treating the supported catalyst-metal oxide composite separated in (b-2);

(d-2) preparing a metal catalyst precursor by mixing a phosphoric acid aqueous solution and a dispersant to the resultant heat treated in (c-2);

(e-2) mixing a binder and a solvent with the resultant prepared in (d-2):

(f-2) providing a method of manufacturing an electrode for a fuel cell, comprising the step of preparing an electrode by coating the resultant prepared in (e-2) on the gas diffusion layer.

According to the above configuration, it is possible to manufacture a fuel cell electrode that also exhibits high ion conductivity even at high temperatures.

According to an aspect of the present invention, there is provided a fuel cell including a cathode, an anode, and an electrolyte membrane positioned between the cathode and the anode, wherein at least one of the cathode or the anode is the electrode for the fuel cell. It provides a fuel cell.

According to the above configuration, it is possible to obtain a fuel cell that maintains high ion conductivity even at high temperatures.

Hereinafter, the present invention will be described in more detail.

An electrode for a fuel cell of the present invention includes a metal catalyst; A carrier for supporting the metal catalyst; A proton conductor made of metal phosphate; A catalyst layer comprising a binder is included. Here, the metal used for the metal phosphate and the metal supported as a catalyst on the carrier are distinguished.

The metal catalyst is platinum (Pt), ruthenium (Ru), tin (Sn), palladium (Pd), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), aluminum (Al), molybdenum (Mo), selenium (Se), tungsten (W), iridium (Ir), osmium (Os), rhodium (Rh), niobium (Nb), tantalum (Ta), lead (Pb), or mixtures thereof. In particular, Pt / Fe alloy, PtWO ₃ , Pt / Ni alloy, Pt / Cr alloy, and Fe / Ni alloy are preferable.

The metal catalyst is supported on a carrier such as carbon particles. As the catalyst carrier, for example, solid particles having a micropore having conductivity and supporting catalyst metal particles, such as carbon powder, may be used. have. Examples of the carbon powder include carbon black, ketjen black, acetylene black, activated carbon powder, carbon nanofiber powder, or a mixture thereof.

In supporting the metal catalyst on the carrier, when too little carrier is used, the active area of the reaction is insufficient and the electrode does not exhibit good performance. When the carrier is excessively used, the catalyst is sintered to increase agglomeration with the surrounding particles, thereby increasing the particle size, thereby decreasing the utilization efficiency of the catalyst. In consideration of the above, the content of the metal catalyst is preferably 10 to 60 parts by weight based on 100 parts by weight of the total weight of the metal catalyst and the carrier.

The content of the binder is preferably 1 to 50 parts by weight, more preferably 5 to 40 parts by weight based on 100 parts by weight of the electrode. When the content of the binder is less than 1 part by weight, the powder is released without coating during electrode production, and when used in more than 50 parts by weight, the proton / electron conductivity of the electrode is inhibited and the electrode is thickened to deteriorate the performance of the electrode. have.

The proton conductor consists of metal phosphate and is distributed with the metal catalyst on the carrier. The metal phosphate is preferably tin phosphate, zirconium phosphate, tungsten phosphate, silicon phosphate, titanium phosphate, or mixtures thereof.

If the content of the metal phosphate is too small, the proton conduction path is not well formed, and the performance of the electrode is greatly reduced. If the content of the metal phosphate is too high, the electron conductivity is reduced and the electrode is thickened to decrease the gas permeability of the catalyst layer. This has the disadvantage of degrading performance. In view of this point, the content of the metal phosphate is 1 to 50 parts by weight, preferably 5 to 30 parts by weight, and more preferably 10 to 20 parts by weight based on 100 parts by weight of the electrode.

The method for manufacturing the fuel cell electrode of the present invention is as follows.

First, the supported catalyst and the metal solution are mixed with stirring at room temperature, and a pH adjuster is added thereto to adjust the pH. The supported catalyst is a catalyst in which the metal catalyst described above is supported on the catalyst carrier described above. The metal solution is a liquid in which salts of metal oxides such as ZrOCl ₂ , Na ₂ WO ₄ , SnCl ₄ , Na ₂ MoO ₄ , SiCl ₄ , and TiCl ₄ are hydrated. The pH adjusting agent may be used any material that can adjust the pH, and specific examples include acids such as hydrochloric acid, sulfuric acid, nitric acid and base such as NaOH, NH ₃ and the like.

When the supported catalyst and the metal solution are mixed and the pH adjuster is mixed so that the pH is 0.5 to 4, the metal oxide precipitates in the form of a hydrate on the surface of the supported catalyst as in Schemes 1 to 3 to form a supported catalyst-metal oxide complex. Form. When the pH is outside the range of 0.5 to 4, the metal oxide does not precipitate well on the supported catalyst. In addition, there is a pH range that precipitates well depending on the type of metal, in the case of tin or zirconium precipitates well at a pH of about 0.5 to 2, and in the case of tungsten or molybdenum it is well precipitated at a pH of about 2-3 .

Scheme 1

ZrOCl ₂ → ZrO ₂ * xH ₂ O

Scheme 2

Na ₂ WO ₄ → WO ₃ * xH ₂ O

Scheme 3

SnCl ₄ → SnO ₂ * xH ₂ O

In a similar manner as above, silicon, molybdenum, and titanium are precipitated in the form of hydrates such as SiO ₂ * xH ₂ O, MoO ₂ * xH ₂ O, TiO ₂ * xH ₂ O. The x is not particularly limited, but is typically 0-4, preferably 0-2.

If the amount of the supported metal catalyst is too small compared to the amount of the metal oxide to be precipitated, the amount of the metal catalyst is too small compared to the amount of the metal phosphate to be produced, resulting in a slow reaction rate and a supported metal compared to the amount of the metal oxide to be precipitated. If the amount of catalyst is too high, the amount of metal phosphate produced is so small that proton conducting paths are not properly formed. In consideration of this point, the weight ratio of the metal oxide precipitated and the metal catalyst supported on the supported catalyst is preferably 1: 2 to 1:20. This can be calculated simply depending on the type of metal catalyst and metal oxide used. The amount of pH adjusting agent added to the reaction varies depending on the type of pH adjusting agent, and the pH is measured by adding the pH adjusting agent to adjust the pH at which the metal oxide is made.

The supported catalyst-metal oxide complex in which the metal oxide is precipitated is separated from the liquid. Separation may be carried out after centrifugation and drying, filtering with a filter paper, but is not limited thereto.

The supported catalyst-metal oxide complex separated above is mixed with an aqueous solution of phosphoric acid and a dispersant. If the amount of the metal oxide is too large compared to the amount of phosphoric acid, the metal phosphate may not be formed well. If the amount of the metal oxide is too small relative to the amount of phosphoric acid, the heat treatment time is long to evaporate the excess phosphoric acid. . In consideration of this point, the amount of the aqueous solution of phosphoric acid is preferably such that the weight ratio of the metal oxide to phosphoric acid is 1: 1 to 1: 6.

The mixing is preferably carried out at a temperature of 100 to 200 ℃, the stirring time is not particularly limited and can be increased or decreased depending on the amount of the material mixed in a range sufficient to evaporate the excess phosphoric acid with the solvent.

As the dispersant, a single component or multicomponent dispersant capable of dissolving an aqueous phosphoric acid solution well and dispersing the supported catalyst-metal oxide complex may be used. Specific and non-limiting examples of the dispersant include water, methanol, ethanol, isopropyl alcohol (IPA), tetrabutyl acetate, n-butyl acetate and the like or alone It can be used in combination, with ethanol and isopropyl alcohol being particularly preferred. In the case of ethanol, the amount of the dispersant is preferably about 2 to 20 times the weight of the separated material. When using water or another dispersant other than ethanol as the dispersant, it is preferable to use a dispersant having a weight corresponding to the volume of the ethanol.

The resultant mixture is heat-treated at about 400 to 700 ° C. for about 0.5 to about 3.5 hours to prepare metal phosphate. When the heat treatment temperature is lower than 400 ° C, the time required for evaporation of phosphoric acid may be excessively long, and when the heat treatment temperature is higher than 700 ° C, the structure of the metal phosphate formed may be modified. If the heat treatment time is too short or too long, the ion conductivity of the resulting metal phosphate tends to be lowered. Thus, an appropriate heat treatment time exists and is typically about 0.5 to 3.5 hours as described above. The heat treatment is preferably performed in a nitrogen atmosphere to prevent oxidation of the catalyst carrier.

After the heat treatment as described above, the supported catalyst-metal phosphate complex in the form of a powder is formed together with the reaction of the following Chemical Formula 4. That is, the metal phosphate is distributed along with the metal catalyst on the surface of the catalyst carrier.

[Formula 4]

MO _y + H ₃ PO ₄ → M _a P _b O _c

MO _y means an oxide of the metal M, and the subscripts a, b, and c depend on the type of metal and the heat treatment temperature. Moreover, the subscript y is an integer of 1-4 determined according to the kind of metal M. Non-limiting examples of the metal phosphate may be SnP ₂ O ₇ , Sn ₂ P ₂ O ₇ , SnHPO _4, etc., if the metal is tin, ZrP ₂ O ₇ , ZrHPO _4, etc., if the metal is zirconium, If the metal is tungsten may be WP ₂ O _{7 and the} like, if the metal is molybdenum may be MoP ₂ O _{7 and the} like.

Meanwhile, the process of mixing the separated supported catalyst-metal oxide complex with an aqueous solution of phosphoric acid and a dispersant and the heat treatment following thereafter may be performed in reverse order.

In other words, the supported catalyst-metal oxide composite separated from the supported catalyst-metal oxide composite may be subjected to a first heat treatment, and the heat-treated supported catalyst-metal oxide composite may be mixed with an aqueous phosphoric acid solution and a dispersant. At this time, the heat treatment conditions and mixing conditions with the aqueous solution of phosphoric acid and the like are the same as the heat treatment conditions and mixing conditions described above.

A binder or a solvent is added to the supported catalyst-metal phosphate composite prepared above and mixed to prepare a liquid or slurry phase for preparing an electrode. In this case, when the content of the binder is too small, the powder is not coated when the electrode is manufactured and falls off, and when used too much, the proton / electron conductivity of the electrode is inhibited and the electrode is thickened to deteriorate the performance of the electrode. In consideration of this point, the weight ratio of the binder and the supported catalyst-metal phosphate composite is preferably 1: 1 to 1: 100. As the binder, a binder that is widely used can be used. Non-limiting examples include Cytop manufactured by Asahi Glass Co. The solvent acts as a dispersant, and there is no particular limitation on the content, so long as it forms an slurry phase capable of coating as a result of mixing. In addition, the higher the content of the solvent, the thinner the electrode to be manufactured, the smaller the content of the solvent, the thickness of the electrode to be prepared should be considered. As a solvent, a dispersant which is commonly used may be a kind which does not dissolve metal phosphate. Non-limiting examples include INT-340SC manufactured by INT Screen.

The resultant mixture prepared as above is applied onto the gas diffusion layer. The gas diffusion layer may be, for example, carbon paper, more preferably water repellent carbon paper, even more preferably water repellent carbon paper or carbon cloth coated with a water repellent carbon black layer. .

The water repellent treated carbon paper contains about 5 to about 50 wt% of a hydrophobic polymer such as PTFE, and the hydrophobic polymer may be sintered. The water repellent treatment of the gas diffusion layer is to secure access passages for the polar liquid reactant and the gas reactant at the same time.

In the water-repellent carbon paper having the water-repellent carbon black layer, the water-repellent carbon black layer contains about 20 to about 50% by weight of hydrophobic polymer such as PTFE as the carbon black and the hydrophobic binder. It is attached to one surface of the same water repellent treated carbon paper. The hydrophobic polymer of the water repellent treated carbon black layer is sintered.

The slurry is applied to one surface of the gas diffusion layer to form an unreduced catalyst layer. When the gas diffusion layer is a water repellent treated carbon paper having a water repellent treated carbon black layer, the slurry is applied on the water repellent treated carbon black layer.

Examples of the method for applying the slurry include printing, spraying or painting, doctor blading, and the like, but are not necessarily limited thereto. The coating amount or coating thickness of the slurry is not particularly limited, and is appropriately adjusted in consideration of the composition of the slurry, the catalyst supporting amount of the electrode to be obtained, and the like.

The electrode coated on the diffusion layer as described above is completed by the electrode by drying in a heating apparatus having a heating space, such as an oven or a furnace. The temperature of the heating device is 40 to 180 ℃, the drying time is preferably 40 minutes to 3 hours.

The electrode manufactured as described above may be used as an anode and / or a cathode according to a conventional method for manufacturing a fuel cell, thereby manufacturing a fuel cell according to the present invention. A fuel cell of the present invention includes a cathode, an anode, and an electrolyte membrane positioned between the cathode and the anode, wherein at least one of the cathode and the anode includes a metal phosphate.

As will be appreciated by those skilled in the art, the metal phosphate proton conductors of the present invention can be used in fuel cells as well as other electrochemical devices. Examples include electrochemical sensors, water electrolysis devices, and the like.

Hereinafter, the structure and effects of the present invention will be described in more detail with specific examples and comparative examples, but these examples are only intended to more clearly understand the present invention and are not intended to limit the scope of the present invention.

<Example 1>

1.0 g (50% Pt) of platinum / carbon supported catalyst was dissolved in 25 ml of a metal solution (0.1 M) in which ZrOCl ₂ was dissolved, and then pH was continuously measured while dropping ammonia water with stirring of the solution. When the pH reached 1, the dropwise addition of ammonia water was stopped, and the mixture was stirred at room temperature for 2 hours. The mixed liquid was filtered through a manure to separate the supported catalyst-metal oxide complex, and the separated supported catalyst-metal oxide complex was washed twice with water. Then, the washed supported catalyst-metal oxide composite was dried at 200 ° C. for 2 hours, and then heat-treated at 550 ° C. for 1 hour. The result was mixed with 1.0 g 105% aqueous phosphoric acid solution and 7 g of ethanol at 140 ° C. for 1 hour. The mixed material was further mixed with stirring at 180 ° C. for 1 hour.

The mixed liquid was placed in a furnace at 600 ° C. and heat treated for 1 hour.

As a result of performing XRD analysis on the solid powder remaining after the heat treatment, a graph as shown in FIG. 1 was obtained. From the XRD pattern of FIG. 1, it can be seen that platinum and ZrP ₂ O ₇ are present together in the powder.

<Examples 2 to 6>

After dissolving 1 g of platinum / carbon supported catalyst (50% Pt) in 22 ml of a metal solution (0.05 M) in which ZrOCl ₂ was dissolved, pH was continuously measured while dropping ammonia water with stirring of the solution. When the pH reached 1, the dropwise addition of ammonia water was stopped, and the mixture was stirred at room temperature for 30 minutes. The mixed liquid was filtered through a manure to separate the supported catalyst-metal oxide complex, and the separated supported catalyst-metal oxide complex was washed twice with water. Then, the supported catalyst-metal oxide composite was dried at 200 ° C. for 1 hour. The result was mixed with 1 g of 105% aqueous phosphoric acid solution and 7 g of ethanol. The mixed material was mixed with stirring for 1 hour at 180 ° C. The amount of the phosphoric acid aqueous solution was adjusted to achieve the weight ratio shown in Table 1 with the platinum catalyst supported on the amount of phosphoric acid.

The mixed liquid as described above was put into a heating furnace at 500 ° C. and heat treated for 30 minutes.

The solid powder remaining after the heat treatment was mixed with the binder and the solvent in the weight ratio shown in Table 1 below, and stirred well for 2 hours. The slurry produced by stirring was applied to the water-repellent carbon paper coated with the water-repellent carbon black layer, and dried in an oven at 60 ° C. for 1 hour and 15 minutes in an oven at 150 ° C. to complete the electrode.

A fuel cell was manufactured by a conventional method using the electrode prepared as described above. The potential and resistance at the current density of 0.2 A / cm ² were measured for the manufactured fuel cell. The results are listed in Table 1 below.

TABLE 1

Binder weight ratio (% by weight) Phosphoric Acid / Platinum Weight Ratio Potential (V) Resistance (mΩ) Example 2 4.0 0.3 0.517 23.5 Example 3 3.8 1.5 0.613 12.8 Example 4 7.5 0.48 0.516 19.0 Example 5 7.5 1.6 0.603 9.7 Example 6 5.7 1.0 0.592 15.3

As can be seen from Table 1, the larger the amount of phosphoric acid, the higher the potential and the smaller the resistance. However, if the amount of phosphoric acid increases, the performance will be improved to a certain extent, but the performance will be worse again to some extent. In addition, it can be seen that when the amount of the binder is small, the performance tends to be relatively improved. Similarly, if the amount of the binder is too small, there will be problems in manufacturing and performance as pointed out above.

<Example 7>

An electrode was manufactured in the same manner as in Examples 2 to 6, except that the weight ratio of phosphoric acid / platinum was 1.6 and the content of the binder was 4 wt%. MEA was prepared using the electrode prepared as described above using a PBI membrane, and a fuel cell was constructed using the MEA prepared as described above, flowing hydrogen and air to the cathode and the anode at a temperature of 150 ° C., and measuring the performance. 2 result was obtained.

As can be seen in FIG. 2, it was found to have excellent performance indicating a potential of about 0.61 V at a current density of 0.2 A / cm ² .

Comparative Example

A fuel cell was constructed using a commercial high temperature MEA manufactured by Celanese, and performance was measured in the same manner as in Example 7. As a result, it exhibited a potential of about 0.60 V at a current density of 0.2 A / cm ² .

Although described in detail with respect to preferred embodiments of the present invention as described above, those of ordinary skill in the art, without departing from the spirit and scope of the invention as defined in the appended claims Various modifications may be made to the invention. Therefore, changes in the future embodiments of the present invention will not be able to escape the technology of the present invention.

According to the present invention, when manufacturing a fuel cell electrode using a metal phosphate as a cationic conductor, it is possible to obtain an electrode having excellent ion conductivity under low temperature and high humidity conditions, low electrical resistance, and high potential under the same conditions. As a result, an excellent fuel cell electrode can be obtained.

Claims (19)

Metal catalysts; A carrier for supporting the metal catalyst; A proton conductor made of metal phosphate; A fuel cell electrode comprising a catalyst layer containing a binder and a gas diffusion layer made of a conductive substrate, wherein the content of the metal phosphate is 5 to 30 parts by weight based on 100 parts by weight of the electrode. The fuel cell electrode according to claim 1, wherein the metal phosphate is tin phosphate, zirconium phosphate, tungsten phosphate, silicon phosphate, molybdenum phosphate or titanium phosphate. According to claim 1, wherein the binder is a fuel cell electrode, characterized in that 1 to 50 parts by weight based on 100 parts by weight of the electrode. delete The electrode as claimed in claim 1, wherein the metal phosphate is present on the surface of the carrier in the form of a supported catalyst-metal phosphate complex distributed with the metal catalyst. The method of claim 1, wherein the metal catalyst is platinum (Pt), ruthenium (Ru), tin (Sn), palladium (Pd), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), Iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), aluminum (Al), molybdenum (Mo), selenium (Se), tungsten (W), iridium (Ir), An electrode for a fuel cell, characterized in that osmium (Os), rhodium (Rh), niobium (Nb), tantalum (Ta), lead (Pb), or a mixture thereof. (a-1) preparing a supported catalyst-metal oxide complex in which a supported catalyst consisting of a metal catalyst and a carrier supporting the same and a metal solution are mixed, and adjusting a pH to precipitate a metal oxide of the metal solution on the supported catalyst; (b-1) separating the supported catalyst-metal oxide complex produced in (a-1); (c-1) preparing a metal catalyst precursor by mixing the supported catalyst-metal oxide complex separated in (b-1) with phosphoric acid and a dispersant; (d-1) heat treating the metal catalyst precursor prepared in (c-1) to obtain a supported catalyst-metal phosphate complex; (e-1) mixing the supported catalyst-metal phosphate complex, the binder and the solvent produced by the heat treatment in (d-1): (f-1) A method of manufacturing an electrode for a fuel cell, comprising the step of preparing an electrode by coating the resultant prepared in (e-1) on a gas diffusion layer. (a-2) mixing the supported catalyst and the metal solution on which the metal catalyst is supported, and adjusting the pH to prepare a supported catalyst-metal oxide complex in which the metal oxide of the metal solution is precipitated on the supported catalyst; (b-2) separating the supported catalyst-metal oxide complex produced in (a-2); (c-2) heat treating the supported catalyst-metal oxide composite separated in (b-2); (d-2) preparing a metal catalyst precursor by mixing a phosphoric acid aqueous solution and a dispersant to the resultant heat treated in (c-2); (e-2) mixing a binder and a solvent with the resultant prepared in (d-2): (f-2) A method of manufacturing an electrode for a fuel cell, comprising the step of preparing an electrode by coating the resultant prepared in (e-2) on a gas diffusion layer. The method of manufacturing a fuel cell electrode according to claim 7 or 8, wherein the pH is adjusted to 0.5 to 4 in (a-1) or (a-2). The method for manufacturing an electrode for a fuel cell according to claim 7 or 8, wherein pH is adjusted using hydrochloric acid, sulfuric acid, nitric acid, sodium hydroxide, ammonia or an aqueous solution thereof. The metal oxide of claim 7 or 8, wherein the metal oxide is ZrO ₂ * xH ₂ O, WO ₃ * xH ₂ O, SnO ₂ * xH ₂ O, SiO ₂ * xH ₂ O, MoO ₂ * xH ₂ O or TiO. ₂ * x H ₂ O and x is 0 to 4, characterized in that the manufacturing method of the electrode for fuel cells. The fuel cell electrode according to claim 7 or 8, wherein the weight ratio of the metal oxide and the metal catalyst in (a-1) or (a-2) is 1: 2 to 1:20. Manufacturing method. The method of claim 7 or 8, wherein the dispersant is water, methanol, ethanol, isopropyl alcohol (IPA), tetrabutyl acetate, n-butyl acetate, or these Method for producing an electrode for a fuel cell, characterized in that a mixture of. The method for manufacturing a fuel cell electrode according to claim 7 or 8, wherein the weight ratio of the metal oxide and phosphoric acid in the above (c-1) or (d-2) is 1: 1 to 1: 6. . The method for manufacturing a fuel cell electrode according to claim 7 or 8, wherein the temperature mixed in (c-1) or (d-2) is 100 to 200 ° C. The method of manufacturing a fuel cell electrode according to claim 7 or 8, wherein the heat treatment is performed at 400 to 700 ° C for 0.5 to 3.5 hours. The fuel according to claim 7 or 8, wherein the weight ratio of the binder and the supported catalyst-metal phosphate composite in (e-1) or (e-2) is 1: 1 to 1: 100. Method for producing a battery electrode. The method of claim 7 or 8, wherein the metal catalyst is platinum (Pt), ruthenium (Ru), tin (Sn), palladium (Pd), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), aluminum (Al), molybdenum (Mo), selenium (Se), tungsten (W), iridium (Ir), osmium (Os), rhodium (Re), niobium (Nb), tantalum (Ta), lead (Pb), or a mixture thereof. A fuel cell comprising a cathode, an anode, and an electrolyte membrane positioned between the cathode and the anode, At least one of the cathode or the anode is a fuel cell electrode according to claim 1 characterized in that.

Images